Acinetobacter in fresh faecal samples is related to sperm motility: A case report in Piétrain boars housed on different deep-litter bedding materials.

The swine gastrointestinal tract contains a great variety of microbes, forming a complex and dynamic ecosystem. Various internal and external factors (e.g. age, breed and diet) may influence its composition. This study aimed to investigate the gut microbial diversity of German Piétrain boars housed on different deep-litter bedding materials (regional wood shavings, linen, hemp, spelt husks, and wood shavings) via 16S-rDNA sequencing. Additionally, short-chain fatty acids were analysed using gas chromatography. Fresh faecal samples (n = 80) from 40 Piétrain boars were collected twice during the trial. Although it can be assumed that boars ingest bedding orally, no differences in the microbiome composition could be found. The main phyla were Firmicutes and Bacteroides. Acinetobacter was identified as a biomarker for sperm quality differences (total sperm motility) in breeding boars.

Science-based quality control in boar semen production.

The ever-increasing understanding of sperm physiology, combined with innovative technical advances, continuously furthers the development of boar semen production management. These improvements pave the way for the future implementation of modified quality assurance concepts. This review provides an overview of current trends and new approaches in boar semen production, focusing on: the improvement of hygienic standards, alternatives to the use of antibiotics including the application of cold temperature storage and the utilization of antimicrobial additives, as well as the implementation of new quality control tools. Furthermore, the influence of dilution and temperature management, as well as new possibilities for an improvement of boar semen shipping and storage conditions are reviewed.

Dual use of breeding stallions is possible without affecting the sperm quality.

Artificial insemination (AI) is commonly used in the equine industry to enhance the genetic value in breeding programs and to effectively utilize ejaculates. Many stallions are used as breeding stallions as well as in high-level sports competitions to improve their market value. The goal of the present study was to investigate whether this dual use of stallions influences the animals´ stress levels and/or the quality of their ejaculates. For this purpose, 18 stallions were grouped into two categories: breeding stallions with (BSC = breeding stallion competition), and breeding stallions without secondary use in competitions (BS = breeding stallion). Two ejaculates were collected at a one-week interval and analysed with an extended spectrum of spermatological methods. Furthermore, saliva, as well as seminal plasma samples were taken, and the concentration of cortisol therein was determined. Additionally, dehydroepiandrosterone (DHEA) and the cortisol/DHEA ratio were analysed and calculated for seminal plasma. After statistical analysis of the correlations and interdependences between the two groups, the results showed that the BSC group had significantly higher saliva cortisol levels (p = .027) and tendentially higher DHEA concentrations in their seminal plasma (p = .056). No difference between BS and BSC could be found in regard to the sperm quality parameters and the cortisol concentration in seminal plasma samples. It can be concluded that while active participation in competitions represents a stress factor, the dual use of stallions in breeding programs and sports competitions is possible without negative effects on their sperm quality.

Bacterial killing activity and lysozymes: A stable defence mechanism in stallion seminal plasma?

During insemination, bacterial contamination of the ejaculate can lead to reduced sperm quality and transmission of pathogens to the female, thus should be avoided. The semen of a variety of animal taxa possess antimicrobial properties against a wide range of bacterial species through antimicrobial molecules, such as lysozyme, but their variance and the factors influencing it are unknown for most species. In this study, the antibacterial defence (bacterial killing activity (BKA) against Escherichia (E.) coli and Staphylococcus (S.) aureus as well as lysozyme concentration) was studied in seminal fluid from two consecutive ejaculates of 18 stallions. All ejaculates showed BKA against the tested bacteria, which correlated between the two consecutive ejaculates (rS  = 0.526, p = .025 for E. coli and rS  = 0.656, p = .003 for S. aureus) and appeared to be stable over the tested period. The lysozyme concentration (LC) showed no significant correlation between the consecutive ejaculates (rS  = 0.161, p = .681). However, LC had a positive correlation to the ratio of apoptotic spermatozoa within the ejaculates (rS  = 0.426, p = .019). In contrast to other livestock (e.g., boar, bull), the BKA in stallion semen did not correlate significantly with the age of the animal nor sperm quality characteristics.

Reprotoxic effects of fenpropimorph on the fertilizing potential of AI boars: A case study.

This case study describes the effects of a contamination of boar bedding material with reprotoxic compounds in an AI centre in southern Germany. The origin of the investigations was an extreme decline in the production output of the boars. In July 2021, more than 54% of boars were not in production and over 45% of ejaculates had insufficient sperm quality and quantity, which is a significant drop in comparison with the other months. This drop was accompanied by oligozoospermia (azoospermia), asthenozoospermia and teratozoospermia. Through intensive troubleshooting, the changes could be attributed to fenpropimorph, an ergosterol biosynthesis-inhibiting fungicide with reprotoxic potential, which was found in the sawdust used as bedding as well as in liver samples of affected animals, reaching a concentration (mean ± SD) between 0.20 ± 0.36 mg/kg and 0.019 ± 0.001 mg/kg respectively. Furthermore, autopsy findings revealed hyperaemia of the testis, histologically focal degeneration of the germinal epithelium and signs of reduced spermatogenesis and spermiogenesis.

Live cells are not affected by dead sperm in liquid boar semen: New insights based on a thermo-resistance test.

This study evaluated the effect of different proportions of dead spermatozoa on the quality of liquid boar semen during a thermo-resistance test (TRT). After 3 days of storage (17°C), 54 conventional artificial insemination semen doses (~23 × 106 sperm/ml in ~88 ml of BTS) were split into three 15 ml-treatments (25%, 50%, and 75% dead sperm cells) by mixing two subsamples containing 75% (I) and 0% (II) of live cells. Spermatozoa were evaluated after TRT at 30 (on-test) and 300 min (off-test) incubation at 38°C. At the on-test, treatments of 25%, 50%, and 75% dead sperm cells showed medians for total sperm motility of 77.6%, 50.2%, and 25.6%, respectively. Considering the absolute variation of sperm motility during TRT, doses with 25% dead sperm lost more percentage points (pp) (-9.4 pp) compared to doses containing 50% (-8.2 pp) and 75% dead sperm (-4.5 pp). The lowest loss was observed for doses with 75% dead sperm (p < .01). However, data showed that treatments lost similar proportion of motile cells over the TRT: 25% dead sperm = -11.9%, 50% dead sperm = -16.0%, and 75% dead sperm = -17.5% (p = .31). Regarding the flow cytometry parameters (plasma and acrosomal membrane integrity, mitochondrial activity of cells with intact plasma membrane, high degree of lipid disorder, and apoptotic cells), the absolute variations did not surpass values of -1.8, 3.4, -5.4, and 4.7 pp, respectively. Furthermore, the relative variation suggested that dead sperm did not substantially change their values over the TRT. In conclusion, dead sperm cells did not influence the quality of contemporary live cells during the period and in conditions of a TRT.

Increased mRNA expression of selected pro-inflammatory factors in inflamed bovine endometrium in vivo as well as in endometrial epithelial cells exposed to Bacillus pumilus in vitro.

Endometrial epithelium plays a crucial role in the first immune response to invading bacteria by producing cytokines and chemokines. The aim of this study was to investigate the first inflammatory response of the endometrium in vivo and in vitro. Gene expression of several pro-inflammatory factors and Toll-like receptors (TLR2, -4, -6) was determined in endometrial cytobrush samples obtained from healthy cows and cows with clinical or subclinical endometritis. Endometrial epithelial cells were co-cultured with an isolated autochthonous uterine bacterial strain Bacillus pumilus. Total RNA was extracted from in vivo and in vitro samples and subjected to real-time reverse transcription polymerase chain reaction. CXC ligands (CXCL) 1/2 and CXC chemokine receptor (CXCR) 2 mRNA expression was higher in cows with subclinical endometritis and CXCL3 mRNA expression was higher in cows with clinical endometritis compared with healthy cows. B. pumilus induced cell death of epithelial cells within 24h of co-culturing. The presence of B. pumilus resulted in significantly higher mRNA expression of interleukin 1α (IL1A), IL6, IL8, CXCL1-3 and prostaglandin-endoperoxide synthase 2 in co-cultured cells compared with untreated controls. The maximum increase was mainly detected after 2h. These results support the hypothesis that bacterial infection of endometrial cells might induce prompt synthesis of pro-inflammatory cytokines resulting in a local inflammatory reaction.

Optimizing mode instability in low-NA fibers by passive strategies.

Systematic experimental investigations toward the mode instability (MI) threshold in low-NA fibers are performed. By testing several fibers with varying V-parameters drawn from the same preform, a high degree of reproducibility of the experimental conditions could be achieved. This allows for systematic investigations on isolated parameters influencing the complex behavior of MI. A maximum MI threshold of 2 kW could be demonstrated for the tested fibers, which represents a new record output power for narrow linewidth fiber amplifiers. The MI threshold was found to sensitively depend on the V-parameter for large V-parameters (>2), but to be robust for smaller V-parameters. Furthermore, the fiber bending diameter and the seed excitation conditions were identified to sensitively influence the MI threshold.

Vibration emissions affect the quality of liquid-preserved AI doses in stallions.

Artificial insemination (AI) with liquid-preserved stallion semen is a widely used reproductive technology. As the demand for AI doses of high-class stallions is transnational, they are frequently exposed to long-distance transport. Since recent studies in boars indicated that vibration emissions caused by transport negatively affected sperm quality in vitro, this study questioned whether sperm quality in stallions is similarly impaired. Furthermore, we investigated stallion and extender-related differences in the spermatozoa's resistance to transport-related quality loss. Stallion ejaculates (n = 30) were collected at a German AI center, split in half, and subsequently diluted to a final sperm concentration of 50 × 106 sperm/mL using the semen extenders EquiPlus or Gent (both Minitüb GmbH, Germany). Four 12 mL aliquots of each sample were filled in plastic syringes according to a split-sample design and exposed to vibration (Displacement index Di = 3.0 ± 0.1) at 5 °C for 0 h (control), 3 h, 6 h or 9 h. All samples were stored for four days at 5 °C after transport simulation and analyzed for total sperm motility, thermo-resistance, membrane integrity, and mitochondrial activity determined by flow cytometry as well as the pH. After calculating generalized linear mixed models for each sperm quality trait, a negative impact of the duration of transport simulation could be shown on total sperm motility (P = 0.001), thermo-resistance (P = 0.030), and the pH (P = 0.001). Simulated transport for 6 h and 9 h diminished sperm quality (P ≤ 0.01), with 9 h reducing thermo-resistance by 5 ± 2.2% points (PP) for EquiPlus and sperm motility by 2.2 ± 1.7 PP for Gent compared to the control group. In contrast, samples exposed to vibration for 3 h showed no decline in sperm quality (P > 0.05). The individual stallion influenced every semen trait (P < 0.05) and transport-related losses in sperm thermo-resistance of up to 15.9 PP were demonstrated. Furthermore, EquiPlus was superior to Gent in all semen assessments (P < 0.001). We conclude that in vitro sperm quality is impaired by vibration. As the quality loss depends on the transport time, we recommend keeping shipping time as short as possible especially for spermatozoa of stallions that are susceptible to vibration-induced sperm quality loss.

Effects of vibrations during boar semen transport: Low-temperature transport as a new management tool.

Transport-related vibrations (TV) compromise the quality of conventionally stored (17 °C) boar semen, but knowledge about TV effects after 5 °C transport is insufficient. This study evaluates the effects of TV after novel 5 °C transport compared to a 17 °C control. Ejaculates of 18 fertile Piétrain boars, diluted in a split sample procedure using Androstar Premium® (AP, 5 °C storage) or Beltsville Thawing Solution (BTS, 17 °C storage), were subjected to transport simulation using a laboratory shaker IKA MTS 4. The timing was set according to the respective processing protocols: for 17 °C BTS samples, TV simulation was performed the day of collection, 5 °C AP samples were subjected to TV the day after collection following completion of the established cooling curve to 5 °C. Six samples per ejaculate were exposed to different TV durations (0 h, 3 h, or 6 h) to evaluate the effect on sperm quality (progressive motility (PM), thermo-resistance test (30 and 300 min incubation at 38 °C (TRT30/TRT300)), mitochondrial activity (MITO), plasma membrane and acrosome integrity (PMAI)). Generalized linear mixed models revealed TV (P = 0.021) and storage time (P < 0.001) dependent declines in PM. Direct, pairwise comparisons revealed that 5 °C samples are not affected by TV (P(3 h vs. 6 h transport) = 1.0; P(0 h vs. 6 h transport) = 1.0). They therefore showed superior quality maintenance after TV compared to 17 °C samples (P(3 h vs. 6 h transport) = 0.025; P(0 h vs. 6 h transport) < 0.001). Concluding, low-temperature transport is possible without significant semen quality loss and with better quality maintenance than standard transport.

Selection and direct biomarkers of reproductive capacity of breeding boars.

Efficient management of pig reproduction is paramount for the sustainability and productivity of the global pork industry. Modern artificial insemination (AI) breeding programs have greatly benefited from the integration of advanced selection methods and biomarkers to enhance the reproductive performance of boars. While traditional selection methods have relied soley on boar phenotype, such as growth rate and conformation, modern pig breeding has shifted more and more toward molecular and genetic tools, which are still complemented by phenotypic traits. These methods encompass genomics, transcriptomics, and proteomics. Biomarkers serve as critical indicators of boar reproductive capacity. They can help to identify individuals with superior fertility and aid in the early identification of potential fertility issues, allowing for proactive management strategies. This review summarizes current knowledge of various biomarkers associated with semen quality, sperm function, and overall reproductive fitness in boars. Furthermore, we explore advanced technologies and their potential applications in uncovering novel selection methods and biomarkers for predicting boar fertility. A comprehensive understanding of selection criteria and biomarkers governing boar reproductive capacity is essential for developing effective breeding programs to enhance swine reproductive performance.

Influence of age, breed, and season on the quality of boar semen stored at low-temperature.

In the face of antimicrobial resistance, antibiotic-free, low-temperature storage of boar semen has been well-researched in recent years and promising results have been obtained. With the prospect of establishing this new preservation method in practice, it is important to evaluate a range of factors, possibly influencing the general and/or boar individual preservation suitability for 5 °C storage. The present study aimed to evaluate the influence of boar age (<18 months (n = 29) vs. 18-36 months (n = 68) vs. >36 months (n = 56)), breed (Pietrain (n = 104) vs. Duroc (n = 49)), as well as the influence of season (summer (n = 73) vs. winter (n = 80)) on the quality of boar semen preserved in antibiotic-free Androstar® Premium extender. AI doses were stored at 5 °C after cooling according to an established cooling protocol. In total, 153 ejaculates were analyzed throughout two identical experimental runs in summer and in winter, and the boars were divided into the corresponding sub-groups based on their age and breed. The application of a general linear model (GLM) and subsequent Bonferroni-corrected post hoc tests did not reveal any significant differences in the quality of semen stored at 5 °C between the different age groups. Regarding the season, a difference was found in the progressive motility (PM) at two out of seven analysis time points (P ≤ 0.01), however, this difference in PM was also present in fresh semen (P < 0.001). Most significant differences were found when comparing the two breeds. At six out of seven analysis time points, PM of Durocs was significantly lower than PM of Pietrains. Again, this difference in PM was also recognizable in fresh semen (P < 0.001). No differences were found in plasma membrane and acrosome integrity examined by flow cytometry. In conclusion, our study confirms the feasibility of 5 °C storage of boar semen under production conditions regardless of boar age. While season and breed have an influence on boar semen stored at 5 °C, these differences are not primarily caused by storage temperature, as they were already apparent in fresh semen.

Lifetime and removal reasons for Pietrain boars in European AI centers: a retrospective analysis.

Currently, artificial insemination (AI) is the most common reproductive method used in swine production. The economic profitability of AI centers is closely linked to a boar's retention rate and the purchase of replacement boars. The objectives of this study were to examine data of selection process and lifetime of a total of 6,496 purebred Pietrain AI boars and to analyze the frequency and reasons of removal in eight European countries. Data were obtained from two German boar multiplication farms as well as 53 AI centers from 2018 to 2022. The retention time was analyzed from the selection process until replacement and to the end of the examination, respectively. The selection process of the boars took place at 168 ±â€…5 (mean ±â€…SD) days of age. For further calculations, the removal reasons were divided into nine groups: breeding (BR), died (DI), euthanasia (EU), health (HE), genetics (GE), low libido (LI), sperm quality (SQ), structure (ST), and other (OT). Overall, 56.1% of the examined boars were removed, with 17.5% being removed within the same year they entered the AI center. The annual removal rate for the 53 AI centers averaged 42.4%. The most frequent removal reason was low SQ (45.1%), followed by genetics (28.6%) and low libido (10.6%). The highest relative frequency of removals was observed for an age of 2 yr (34.0%). The highest removal risk was calculated for boars in Czech AI centers (P < 0.001), while the lowest removal risk occurred in Dutch (P = 0.006) and Portuguese AI centers (P = 0.01). The comparison of removal groups revealed, inter alia, higher body weight at selection process for the BR group (117.9 ±â€…9.0 kg) and longer quarantine periods for LI group (45.9 ±â€…17.6 d). Boars in the GE group were characterized by the oldest age at removal (934.0 ±â€…272.8 d) and longest period of exploitation (672.5 ±â€…266.8 d). The results could be helpful to detect the most common reasons for production failure of AI Pietrain boars and beneficial for establishing an economical removal policy in AI centers and for improving boar management through problem-based selection in boar multiplication farms.

Unsurprisingly, the removal of boars from artificial insemination (AI) centers affects the centers' economic performance and production efficiency. An analysis of reasons for removal is beneficial for an optimal removal policy and can help detect health problems that could be occurring in the herd. The aim of this study was to analyze data of selection process and removal, lifetime and removal reasons of 6,496 Pietrain boars in 53 European AI centers. The most common reason for boar removal was poor sperm quality, followed by genetics and low libido. The highest retention rate with increasing age was calculated for boars removed due to genetics, whereas boars removed because of low libido were characterized by the lowest probability to remain in the herd. Hazard analysis indicates that the removal risk for boars is influenced by the production process and differs between European countries.

Influence of Equilibration Time and Bull-Specific Extender for Cryopreservation on Semen Quality and Fertility in German Holstein Friesian Bulls: A Controlled Field Trial.

Equilibration with an extender is necessary to allow cryopreservation of bovine sperm. The aim of trial 1 was to assess the effect of 24 h versus 4 h equilibration time with three different extenders on sperm quality and to select the preferred extender for each bull. The aim of trial 2 was to investigate the effect of using a 24 h equilibration time with a bull-specific extender on field fertility. For trial 1, three ejaculates each from eight Holstein Friesian breeding bulls were used as the split-sample, including two equilibration times (4 h and 24 h) and three extenders (BioXcell, Triladyl, and OptiXcell). For trial 2, from 5 to 10 ejaculates from the same bulls were collected and treated (split-sample) as BioXcell with 4 h equilibration and either Triladyl or OptiXcell, both with 24 h equilibration. A total of 11,059 straws were used for insemination of cows and heifers. For Triladyl, progressive sperm motility, acrosome defects, and plasma membrane and acrosome integrity improved with a 24 h compared to a 4 h equilibration time. Four bulls each were used with Triladyl and OptiXcell for trial 2. In trial 2, non-return rates did not differ among groups. Therefore, using a 24 h equilibration time might improve in vitro sperm parameters, depending on the extender used. Moreover, it would be possible to change from 4 h to 24 h equilibration time without impairing field fertility.

Comparative Assessment of the Stress Response of Cattle to Common Dairy Management Practices.

While studies have been conducted examining the stress response of dairy cattle to individual acute and chronic stressors, the results are difficult to compare due to differences in study design and analysis methods. The aim of the present study was to conduct a comparative assessment of the impact of eight common stimuli: artificial insemination (AI), embryo transfer (ET), morning milking (MM), evening milking (EM), veterinary examination (VE), ultrasound examination (US), hoof trimming (HT), and natural breeding (NB) on the hypothalamic-pituitary-adrenal axis and milk production of 24 Holstein-Friesian cattle. After random allocation into control and treatment groups, a total of five blood samples were collected 40 min (Ba1) and 20 min (Ba2) prior to stimulus application, immediately following the stimulus (St), as well as 20 min (Re1) and 40 min (Re2) post-stimulus. A comparison between the overall serum cortisol concentrations in the treatment groups showed a significant difference between HT to AI (p = 0.006), ET (p = 0.010), MM (p = 0.021), VE (p = 0.009), EM (p = 0.007), and US (p = 0.010), except for NB (p = 0.542). There is no significant difference between the control groups (p > 0.05). The stimuli HT (p < 0.001) and NB (p < 0.001) showed significant increases in cortisol following stimulus application, and the levels failed to decrease significantly by sample Re2. No significant differences in daily milk yield (kg) were measured amongst the tested stimuli (p = 0.472) nor amongst the groups 'Control', 'Treatment' and 'no stimulus' (p = 0.350). In conclusion, when factors such as increased physical activity, novel social interaction, sexual arousal, and a more intense restriction of movement are present, the animal's perceived controllability and predictability might decrease, affecting the animal's response to stress. Treatments carried out while animals are restrained in a headlock while remaining within their regular group likely result in a less intense activation of the HPA axis.

Analysis of artificial insemination center management factors that contribute to sperm parameters and boar longevity with a major focus on PGF2α treatment.

Artificial insemination (AI) centers' economic profitability is directly impacted by the amount of high-quality sperm doses. Many internal and external factors contribute to the quality of ejaculates. To enhance the libido and to reduce the time that is required to train boars for semen collection, prostaglandin products are used routinely at AI centers. The objectives of this study were to analyze sperm parameters of 40,765 ejaculates and the survival of 406 PGF2α-treated and 417 untreated AI boars of five breeds (Duroc [DU], Large White [LW], Landrace [LR], Pietrain [PI], and Large White Sire Line [LS]). Data were assessed in one AI center in Switzerland from 2018 to 2022 and sperm parameters were determined by computer-assisted sperm analysis immediately after semen collection. For further calculations, the ejaculates were divided into four groups depending on the boar's age at semen collection day: 7 to 11, 12 to 18, 19 to 24, and 25 to 87 mo. Along with the boar age, breed, season, and semen collection frequency even the treatment with PGF2α had significant influence on sperm parameters. Overall, 19.5% ejaculates were collected after PGF2α treatment. For every age and breed group, higher ejaculate volume was found for untreated boars than for PGF2α-treated boars (P < 0.001). Higher values for total and progressive sperm motility, total sperm number, and the proportion of morphologically normal sperm were observed in untreated boars across several age and breed groups. Only for sperm concentration, higher values were found for treated boars older than 11 mo (P < 0.001) and the breeds DU, LW, and LR (P < 0.001). The chance of ejaculates being rejected for AI purposes because of low sperm quality was 21% greater for treated boars. There was no difference in survival between treated and untreated boars. The hazard for boar removal increased with decreasing age at first semen collection and decreasing semen collection frequency. The results reveal better sperm quality for untreated boars than for PGF2α-treated boars, which might indicate that the underlying fertility of boars necessitating treatment is inferior compared to boars that can be collected without further treatment. Therefore, AI boar stations that are aiming to reduce PGF2α treatment should pay special attention to high libido and fertility of young prospective AI boars.

In many artificial insemination (AI) centers, prostaglandin products are used routinely to enhance the mounting behavior of boars with libido problems and to expedite the training of young boars to mount an artificial sow and allow semen collection. Recent studies examining the influence of prostaglandin-F2α (PGF2α) on sperm quality are still rare and present low sample sizes and diverse results. The aim of this study was to analyze AI center management factors that affect boar longevity and sperm parameters with a main focus on PGF2α treatment. The analysis compares sperm parameters of 40,765 ejaculates and the longevity of 823 PGF2α-treated and untreated AI boars based on 4 yr of data. Sperm parameters were assembled by computer-assisted sperm analysis. The results revealed that not only boar age, breed, semen collection technician, season, and the monthly collection frequency contributed significantly to the sperm parameters, but also the treatment with PGF2α. While we found at least greater values for ejaculate volume, total sperm number, and total and progressive motility for untreated boars, the longevity at AI center was not affected by PGF2α treatment. Rather, the boar's age at first semen collection session and the semen collection frequency had significant influence on the survival time of AI boars.

Effect of using liquid semen on fertility in German Holstein Friesian dairy cattle: A randomized controlled clinical trial.

Low fertility rates in lactating dairy cows as well as restricted availability of semen doses of young bulls with high genetic merit are two major problems in the reproduction of dairy cows. By using liquid semen (LS), the number of doses per ejaculate can be increased. One of the challenges of optimizing the reproductive performance of dairy cows is the phenomenon of variable estrus lengths. The objective of this study was to determine whether the use of LS affects pregnancy outcome of dairy cows with delayed ovulation, when compared with frozen semen (FS). A randomized controlled clinical trial was implemented. In a split-sample procedure, 131 ejaculates were processed into LS (Caprogen, LIC, New Zealand) and FS (BioXcell, IMV, France). Both semen types of each ejaculate were inseminated under the same field conditions to cows showing natural or induced heat. Cows and semen type were allocated according to the last digit of the cows identification number (even = frozen semen, odd = liquid semen). Inseminations (n = 667) were conducted after localization of the pre-ovulatory follicle. Determination of ovulation was performed 24 h post AI per transrectal ultrasonographic examination. Ovulations were classified as delayed when the pre-ovulatory follicle was still present at ovulation control. The prevalence of delayed ovulations was 25.2%. Data of 667 inseminations were analyzed with a generalized linear mixed model including semen type (P = 0.016), parity (P = 0.014), backfat thickness (P = 0.006), estrus induction (P = 0.010), ovulation (P = 0.265) and the interaction term 'semen type by ovulation' (P = 0.094). Overall, a higher pregnancy per AI (P/AI) of LS (45.4%) than P/AI of FS (33.7%) was found. In cases of delayed ovulations, use of LS resulted in higher P/AI (46.8%) compared with FS (27.7%; P = 0.017). We concluded that the fertilizing capacity of LS in prolonged intervals from AI to ovulation might be greater when compared with FS and could be an efficient tool to improve fertility of lactating dairy cows with delayed ovulations.

Comparison of deep-litter bedding materials and analysis of semen traits in Piétrain boars: A randomized controlled field study.

External factors can affect reproductive traits of breeding boars and especially the sensitive process of spermatogenesis. The aim of this study was to investigate probable influences of bedding materials (chipsy wood shavings (CWS), hemp straw (HS), linen straw (LS), spelt husks (SH), and regional wood shavings (RWS)) on semen traits of 40 randomly selected Piétrain boars (8 boars per group, age: 2.35 ± 1.23 years). After a six-week adaptation period, 40 fresh semen samples were collected weekly for four weeks and diluted in BTS (4 consecutive ejaculates per boar, 32 samples per group, 160 samples in total). Semen samples were analyzed using an extended range of spermatological methods (e.g., computer-assisted sperm analysis and flow cytometry). Generalized linear mixed models for each sperm parameter as well as the area under the curve for total sperm motility and thermo-resistance test were calculated. Materials LS and SH exceeded the standard maximum level for pesticide residues (VO (EG) No. 396/2005). Materials HS and LS presented the highest water-binding capacity of 413 % and 357 %, respectively, while SH showed the lowest value of 250 %. There were no significant (P > 0.05) differences between groups in any sperm characteristic, therefore indicating that bedding material had no influence on sperm quality. For most semen traits, however, we found significant (P ≤ 0.001) differences between sampling weeks. Based on pesticide results, we suggest CWS, RWS, or HS as possible bedding materials for pig production farms in the future. Furthermore, we strongly recommend a quality analysis of any new bedding material before use in swine husbandry.

Lipid alterations by oxidative stress increase detached acrosomes after cryopreservation of semen in Holstein bulls.

The nearly exclusive use of cryopreserved semen in cattle breeding enables long shipping distances, higher storage times, quarantine to avoid germ transmission and easy dispersal of high genetic value bulls. Spermatozoa from bulls are well freezable and improvement of cryopreservation protocols over decades has led to high semen quality. However, there is still some loss of spermatozoa in each semen dose due to detached acrosomes after thawing. There are even individual bulls with extremely high numbers of detached acrosomes after cryopreservation, called "bad freezers". This study screened 1092 ejaculates from 59 Holstein bulls for the difference in detached acrosomes before and after cryopreservation (ΔAC). The individual bull influenced ΔAC (P < 0.001) and allowed selection for individuals with repeatedly low ΔAC (good freezers) or high ΔAC (bad freezers). Good freezers were superior to bad freezers in a thermo-resistance test (78.2% vs. 33.6% total motility, respectively, P = 0.047) and had higher non-return rates (NRR: 46.8% vs. 40.8%, respectively, P = 0.016). Since oxidative stress is one possible explanation for premature acrosome reaction, the radical reduction capacity of the seminal fluid was measured, finding that this parameter was reduced in bad freezer bulls during cryopreservation (P = 0.043). Analysis of lipid species in sperm cells by matrix-assisted laser desorption and ionization time-of-flight mass spectrometry (MALDI-TOF MS) showed a reduction of ether lipids and plasmalogens as well as an increase in formyl-lysophosphatidylcholines only within the bad freezers during cryopreservation (P = 0.043). In conclusion these findings show, that lipid alteration caused by oxidative stress is one essential reason for highly augmented acrosome reacted spermatozoa in bad freezer bulls. Therefore, increased use of antioxidants in the extender could be a possible starting point for developing individualized extenders for bad freezer bulls of high genetic value, in order to raise sperm quality after cryopreservation even in those bulls.

Intensity and Duration of Vibration Emissions during Shipping as Interacting Factors on the Quality of Boar Semen Extended in Beltsville Thawing Solution.

Vibration emissions during the transport of boar semen for artificial insemination (AI) affect sperm quality. In the present study, the common influence of the following factors was investigated: vibrations (displacement index (Di) = 0.5 to 6.0), duration of transport (0 to 12 h) and storage time (days 1 to 4). Normospermic ejaculates were collected from 39 fertile Pietrain boars (aged 18.6 ± 4.5 months) and diluted in a one-step procedure with an isothermic (32 °C) BTS (Minitüb) extender (n = 546 samples). Sperm concentration was adjusted to 22 × 106 sperm·mL-1. Extended semen (85 ± 1 mL) was filled into 95 mL QuickTip Flexitubes (Minitüb). For transport simulation on day 0, a laboratory shaker IKA MTS 4 was used. Total sperm motility (TSM) was evaluated on days 1 to 4. Thermo-resistance test (TRT), mitochondrial activity (MITO) and plasma membrane integrity (PMI) were assessed on day 4. Sperm quality dropped with increasing vibration intensity and transport duration, and the effect was enhanced by a longer storage time. A linear regression was performed using a mixed model, accounting for the boar as a random effect. The interaction between Di and transport duration significantly (p < 0.001) explained data for TSM (-0.30 ± 0.03%), TRT (-0.39 ± 0.06%), MITO (-0.45 ± 0.06%) and PMI (-0.43 ± 0.05%). Additionally, TSM decreased by 0.66 ± 0.08% with each day of storage (p < 0.001). It can be concluded that boar semen extended in BTS should be transported carefully. If this is not possible or the semen doses are transported a long way, the storage time should be reduced to a minimum.